1. Field
One embodiment of the present invention relates to a technique associated with die casting.
2. Description of the Related Art
A die-casting die of the cold-chamber die casting system is provided with a fan gate for guiding molten metal to a product section (i.e., section in which a product is to be cast) inside the die. The fan gate includes a biscuit section for receiving molten metal from an injection apparatus of a casting machine, a runner section for guiding the molten metal from the biscuit section to the product section, and a fin section for accelerating the flow speed of the molten metal by sharply reducing the thickness.
The product section includes a product central section corresponding to a region straightly downstream from the biscuit section in the direction of the flow of the molten metal, and product side sections out of the product central section. The fan gate is provided with a delta section for supplying the flow of the molten metal liable to concentrate in the product central section to the product side sections
This delta section is a convex section provided, for example, between the biscuit section and the product central section. The molten metal flowing from the biscuit section toward the product central section collides against the delta section to be apportioned to the right and left product side sections. if the delta section is not provided, the flow of the molten metal concentrates in the product central section, and the product central section becomes overfilled. On the other hand, in the right and left product side sections, there is the possibility of shortage of filling, uneven filling, or a crack being caused resulting from incomplete fusion.
In Jpn. Pat. Appln. KOKAI Publication No. 2002-45956, a fan gate of a die provided with a delta section is disclosed. This fan gate includes a biscuit section, runner section, and gate sections (corresponding to the fin section). The runner section is partially provided with the gate sections, and only several specific parts of the runner section are connected to the product section. In other words, parts which are not provided with the gate sections serve as delta sections.
By the way, when such a delta section is provided, the molten metal liable to concentrate in the product central section is caused to branch into the product side sections, and the shortage of filling at the product side sections is improved. However, the molten metal divided by the delta section is joined together in the product section again, and in that process, collision between the molten metal components occurs. At this time, there is the possibility of a phenomenon in which air inside the die is rolled up in the molten metal (so-called gas inclusion) being caused. If this gas inclusion occurs, there is the possibility of defective casting called a mold cavity, defective filling, or a molten metal wrinkle being caused. The molten metal wrinkle is also called cold shut, which is a pattern left on the surface of a cast product.